1. Field of the Invention
The present invention relates to a ground metal fitting and a ground structure for jacks of electronic devices, provided so as to enable a single or plural plug or plugs to be connected to a part of an electronic device through a single or plural hole or holes made in a cabinet thereof.
2. Related Art
As shown in FIGS. 7(a) and 7(b), a front panel or a rear panel of an electronic device is provided with jacks for connecting the electronic device to an external electronic device. FIG. 7(a) shows jacks provided in the front panel, and FIG. 7(b) shows jacks provided in the rear panel. When the jacks are provided in the front panel, the jacks include a picture input jack “j”, left and right jacks “k”, “l” for voice input jacks, and a jack “m” for an S-terminal.
On the other hand, when the jacks are provided in the rear panel, the jacks include an image input jack “j”, left and right jacks “k”, “l” for voice input jacks, a jack “m” for an S-terminal, and input and output jacks “n”, “o” for an antenna. These jacks are grounded so as to prevent the electronic device from encountering troubles of electromagnetic waves. There are various ground structures for these jacks. As a general ground structure, a metal fitting is fitted around an outer circumference of a cylindrical portion of a jack housing, and the jacks are connected to the rear panel via the metal fitting.
As shown in FIGS. 8(a) to 8(c), a “JACK WITH GROUND HARDWARE” disclosed in JP-A-11-121105 is structured by providing an inner leaf spring “b” and an outer leaf spring “c” on a ground metal fitting “a”, holding the ground metal fitting “a” between a jack and a terminal panel “d”, bringing the inner leaf spring “b” into contact with a cylindrical portion “e” of the jack, and bringing the outer leaf spring “c” into contact with the terminal panel “d”. However, in this ground structure, a clearance “i” between an outer circumference of the cylindrical portion “e” of the jack and an inner circumference of a hole for the ground metal fitting “a” is large, so that a shielding effect of the ground metal fitting is not satisfactorily high. Since inner leaf springs “b”, “b” . . . are provided on upper, lower, left and right portions of an inner circumferential surface of the hole mentioned above, the intervals at which jacks are arranged become large, and this necessarily hampers miniaturization of the electronic device.
As shown in FIG. 8(d), “ELECTRONIC APPARATUS” disclosed in JP-A-6-76885 is structured by providing a first contact portion “f” and a second contact portion “g” on a ground metal fitting “a”, holding the ground metal fitting between a jack and a terminal panel “d”, engaging the first contact portion “f” with an inner surface of the terminal panel “d”, and engaging the second contact portion “g” with a ground of a cylindrical portion “e” of the jack. Since this ground metal fitting has a three dimensional solid shape having the first contact portion “f” and second contact portion “g”, manufacturing of the ground metal fitting is troublesome. It is not easy to form the ground metal fitting to adapt to a plurality of jacks arranged on a panel of an electronic device. Therefore, these ground metal fittings have to be fixed to respective jacks.
As shown in FIG. 8(e), “ELECTRIC WAVE LEAKAGE PREVENTING STRUCTURE FOR RCA JACKS AND REAR PANELS” disclosed in JP-U-3095000 is provided on a jack with a ground metal fitting “a” connected to a ground terminal, and on a terminal panel “d” with a claw “h”. When the jack is fastened tightly to the terminal panel “d” with a screw, the claw “h” of the terminal panel “d” comes into contact with the ground metal fitting of the jack. In this ground structure, the claw “h” has to be provided on the terminal panel “d”.
Owing to the use of such a ground metal fitting, the jack is in contact with the terminal panel and grounded. However, in case the terminal panel (rear panel) is not a conductive panel, e.g. is a resin panel, it cannot be grounded. Although the rear panel of a cabinet of an electronic device is made of metal in many cases, a resin panel is used for the front panel for the sake of design. Therefore, when jacks are provided on the front surface of a cabinet, the above-described ground structure has problems.
Thus, conventional ground structure for electronic devices have such problems as described above.